Police footage taken from the night officers say a suspect in Arkansas managed to fatally shoot himself in the head – despite having his hands cuffed behind his back – has failed to remove questions over the incident.

Chavis Carter died in the back of a patrol car on 28 July after being picked up in a traffic stop in Jonesboro during which drugs were discovered in the vehicle.

The 21-year-old black man had been searched twice by officers, but a handgun that officers say the suspect later used to shoot himself was not found. Questions have also been raised as to how the left-handed Carter was able to deliver a fatal shot to his right temple while in restraints.

On Friday, following a Freedom of Information Act request by multiple news organizations, police released footage of the immediate aftermath of Carter's death.

They had earlier handed over a video taken before the suspect's body was discovered. But that first video failed to provide any answers to the dead man's family, who claim that he was killed by police.

Chavis died from a single gunshot wound to the head.

He had earlier been detained – alongside two other suspects – by officers searching for drugs in the back of a truck they had noticed parked on the street with its lights on.

Having found a set of scales giving off a strong smell of marijuana, and a bag containing a white substance, a check was run on Carter revealing an outstanding warrant for the Mississippi resident, according to copy of the police report posted online.

The suspect was then handcuffed with his hands behind his back and led to the back seat of a patrol car.

It was while in restraints and in the rear of the police car that Carter is alleged to have shot himself.

In an apparent copy of the official incident report posted online by TheGrio.com, an officer states that he heard a "loud thump and a metallic sound" while speaking to the two other suspects.

But he said he dismissed it as the sound of a car driving over a piece of metal on the roadway.

It was only after the two other suspects were sent away that Carter's body was discovered, one officer recorded.

"We went to the rear passenger side door, opened it and I observed Carter in a sitting position slumped forward with his head in his lap.

"There was a large amount of blood on the front oh his shirt, pants, seats and floor. His hands were cuffed behind his back."

The incident has raised questions, not least over how officers apparently failed to find the gun on Carter during an initial search.

It has also been considered suspicious that the suspect died as a result of a gunshot wound to the right temple, as Carter was left handed and handcuffed at the time.

The dead man's mother, Teresa Carter, has accused police of a cover up.

Amid growing media interest in the case, police agreed to release footage from a dashboard camera that captured events leading up to Carter's death. It shows the suspect being led to a patrol car.

But it failed to provide any clues as to what happened after he was put in the vehicle.

"There's still nothing in there about what actually happened with Chavis," Benjamin Irwin, a lawyer for the Carter family, said.

A second batch of video clips was released Friday. It contains an audio exchange between two unseen men – thought to be officers – shortly after the suspect's body is discovered.

"He was breathing a second ago," says one, while another is heard stating: "I patted him down. I don't know where he had it hidden."

The Jonesboro police department has asked the FBI to assist in its investigation into the incident

Special agent Kimberly Brunell told the Guardian earlier this month: "We are monitoring the situation and we have received certain information, investigative information has been shared with us."